I am having the same problem. I hit Confirm on the overlay and the blue wait spinner just goes indefinitely. I've tried on both iPhone and desktop.

That was happening to me. I closed my browser and tried again. Seemed to work.

I'm currently having the same Issue. I got to the Xsolla page, and it said something along the lines of "There has been a technical issue."

Edit: Worked after I restarted the browser, and disabled ad-block on the page.

I was able to get through once I turned off the pop up blocker in my iOS Safari options.